import { useState, useEffect, useCallback } from "react";
import {
  Stack,
  Title,
  Tabs,
  Group,
  Button,
  TextInput,
  Textarea,
  Modal,
  Text,
  Select,
  Loader,
  Center,
  Alert,
} from "@mantine/core";
import { useForm } from "@mantine/form";
import { useDisclosure } from "@mantine/hooks";
import {
  IconPlus,
  IconBriefcase,
  IconMap,
  IconCertificate,
  IconHash,
  IconInfoCircle,
} from "@tabler/icons-react";
import { useTranslation } from "react-i18next";
import {
  notify,
  useErrorHandler,
  AdvancedTable,
  useServerTable,
  ModalFooter,
  PageLoader,
} from "@ema-platform/ui";
import { LocationPage } from "../../../location/pages/LocationPage";
import { CertificationPage } from "../../../certification/pages/CertificationPage";
import { NumberFormatTab } from "../../components/NumberFormatTab";
import {
  useGetOrganizationsQuery,
  useGetProfessionsQuery,
  useCreateProfessionMutation,
  useUpdateProfessionMutation,
  useDeleteProfessionMutation,
} from "../../api/configuration-api";
import type { Profession } from "../../types/configuration";
import { professionColumns } from "./columns";
import { professionActionsColumn } from "./actions";
import { PageHeader } from '@ema-platform/ui';

interface ProfFormValues {
  nameEn: string;
  nameAm: string;
  descEn: string;
  descAm: string;
  departmentId: string;
}

interface ProfFormProps {
  editingProf: Profession | null;
  deptOptions: { value: string; label: string }[];
  isSubmitting: boolean;
  onSubmit: (values: ProfFormValues, isEdit: boolean) => void;
  onCancel: () => void;
}

function ProfessionForm({
  editingProf,
  deptOptions,
  isSubmitting,
  onSubmit,
  onCancel,
}: ProfFormProps) {
  const { t } = useTranslation();
  const form = useForm<ProfFormValues>({
    initialValues: {
      nameEn: "",
      nameAm: "",
      descEn: "",
      descAm: "",
      departmentId: "",
    },
    validate: {
      nameEn: (v) => (!v ? t("configuration.validation.nameEnRequired") : null),
      nameAm: (v) => (!v ? t("configuration.validation.nameAmRequired") : null),
      departmentId: (v) =>
        !v ? t("configuration.validation.departmentRequired") : null,
    },
  });

  useEffect(() => {
    if (editingProf) {
      form.setValues({
        nameEn: editingProf.name.en,
        nameAm: editingProf.name.am,
        descEn: editingProf.description.en ?? "",
        descAm: editingProf.description.am ?? "",
        departmentId: editingProf.departmentId,
      });
    }
  }, [editingProf]);

  const handleSubmit = form.onSubmit((values) =>
    onSubmit(values, !!editingProf),
  );

  return (
    <Modal
      opened
      onClose={onCancel}
      title={
        editingProf
          ? t("configuration.update")
          : t("configuration.addProfession")
      }
      size="md"
    >
      <form onSubmit={handleSubmit}>
        <Stack gap="sm">
          <TextInput
            label={t("configuration.nameEn")}
            placeholder="English name"
            {...form.getInputProps("nameEn")}
            size="sm"
          />
          <TextInput
            label={t("configuration.nameAm")}
            placeholder="የአማርኛ ስም"
            {...form.getInputProps("nameAm")}
            size="sm"
          />
          <Textarea
            label={t("configuration.descEn")}
            placeholder="English description"
            {...form.getInputProps("descEn")}
            size="sm"
            autosize
            minRows={2}
          />
          <Textarea
            label={t("configuration.descAm")}
            placeholder="የአማርኛ መግለጫ"
            {...form.getInputProps("descAm")}
            size="sm"
            autosize
            minRows={2}
          />
          <Select
            label={t("configuration.department")}
            placeholder={t("configuration.selectDepartment")}
            data={deptOptions}
            {...form.getInputProps("departmentId")}
            size="sm"
            searchable
          />
          <ModalFooter>
            <Button variant="default" onClick={onCancel} size="sm">
              {t("configuration.cancel")}
            </Button>
            <Button type="submit" size="sm" loading={isSubmitting}>
              {editingProf
                ? t("configuration.update")
                : t("configuration.create")}
            </Button>
          </ModalFooter>
        </Stack>
      </form>
    </Modal>
  );
}

function ProfessionTab() {
  const { t, i18n } = useTranslation();
  const locale = i18n.language as "en" | "am";
  const { handleError } = useErrorHandler();
  const { data: deptRes } = useGetOrganizationsQuery();
  const { pageIndex, setPageIndex, setQ, pageSize, setPageSize, skip, take } =
    useServerTable({
      pageSize: 10,
    });
  const {
    data: profRes,
    isLoading,
    isFetching,
    isError,
    refetch,
  } = useGetProfessionsQuery(
    `skip:${skip},take:${take},orderBy:createdAt:DESC`,
  );
  const [createProfession, { isLoading: isCreating }] =
    useCreateProfessionMutation();
  const [updateProfession, { isLoading: isUpdating }] =
    useUpdateProfessionMutation();
  const [deleteProfession] = useDeleteProfessionMutation();

  const departments = Array.isArray(deptRes) ? deptRes : (deptRes?.items ?? []);
  // Server now paginates, so the previous client-side `isActive` filter is
  // dropped (it would hide rows outside just this page). Restore it via a
  // server-side `q` filter once the backend field name is confirmed.
  const professions = profRes?.items ?? [];
  const totalCount = profRes?.total ?? profRes?.count ?? professions.length;

  const [editingProf, setEditingProf] = useState<Profession | null>(null);
  const [showProfForm, setShowProfForm] = useState(false);
  const [deleteTarget, setDeleteTarget] = useState<Profession | null>(null);
  const [deleteOpened, { open: openDelete, close: closeDelete }] =
    useDisclosure(false);

  const deptOptions = departments
    .filter((d) => d?.status?.toLowerCase() === "active")
    .map((d) => ({
      value: d.id,
      label: d.name?.[locale] ?? d.name ?? "",
    }));

  const resetProfForm = useCallback(() => {
    setEditingProf(null);
    setShowProfForm(false);
  }, []);

  const handleEditProf = useCallback((prof: Profession) => {
    setEditingProf(prof);
    setShowProfForm(true);
  }, []);

  const handleDeleteProf = useCallback(
    (prof: Profession) => {
      setDeleteTarget(prof);
      openDelete();
    },
    [openDelete],
  );

  const confirmDeleteProf = useCallback(async () => {
    if (!deleteTarget) return;
    try {
      await deleteProfession(deleteTarget.id).unwrap();
      notify.success(t("configuration.deleted"));
      closeDelete();
      setDeleteTarget(null);
    } catch (e) {
      handleError(e);
    }
  }, [deleteTarget, deleteProfession, closeDelete, handleError]);

  const handleProfSubmit = useCallback(
    async (values: ProfFormValues) => {
      const name = { en: values.nameEn, am: values.nameAm };
      const description = { en: values.descEn, am: values.descAm };

      try {
        if (editingProf) {
          await updateProfession({
            id: editingProf.id,
            name,
            description,
            departmentId: values.departmentId,
          }).unwrap();
          notify.success(t("configuration.updated"));
        } else {
          await createProfession({
            departmentId: values.departmentId,
            name,
            description,
          }).unwrap();
          notify.success(t("configuration.created"));
        }
        resetProfForm();
      } catch (e) {
        handleError(e);
      }
    },
    [
      editingProf,
      createProfession,
      updateProfession,
      resetProfForm,
      handleError,
    ],
  );

  const getDeptName = useCallback(
    (deptId: string) => {
      const dept = departments.find((d) => d.id === deptId);
      return dept ? (dept.name?.[locale] ?? dept.name?.en ?? "-") : "-";
    },
    [departments, locale],
  );

  const columns = [
    ...professionColumns(t, locale, getDeptName),
    professionActionsColumn({
      onEdit: handleEditProf,
      onDelete: handleDeleteProf,
    }),
  ];

  if (isLoading) {
    return <PageLoader label="Loading Configuration…" height={400} />;
  }

  if (isError) {
    return (
      <Alert
        icon={<IconInfoCircle size={16} />}
        color="red"
        title={t("configuration.error")}
      />
    );
  }

  return (
    <>
      <Group justify="space-between" align="flex-end" mb="md">
        <Title order={2}>{t("configuration.professionsList")}</Title>
        {!showProfForm && (
          <Button
            variant="light"
            leftSection={<IconPlus size={16} />}
            onClick={() => setShowProfForm(true)}
            size="sm"
          >
            {t("configuration.addProfession")}
          </Button>
        )}
      </Group>

      {showProfForm && (
        <ProfessionForm
          editingProf={editingProf}
          deptOptions={deptOptions}
          isSubmitting={isCreating || isUpdating}
          onSubmit={handleProfSubmit}
          onCancel={resetProfForm}
        />
      )}

      <AdvancedTable
        columns={columns}
        data={professions}
        tableName={t("configuration.professionsList")}
        itemCount={totalCount}
        pageIndex={pageIndex}
        onPageChange={setPageIndex}
        pageSize={pageSize}
        onPageSizeChange={setPageSize}
        refresh={refetch}
        onSearchChange={setQ}
        isLoading={isFetching}
        emptyText={t("configuration.noProfessions")}
      />

      <Modal
        opened={deleteOpened}
        onClose={closeDelete}
        title={t("configuration.confirmDelete")}
        size="sm"
      >
        <Text mb="md">
          {t("configuration.deleteConfirmText", {
            name: deleteTarget?.name?.[locale] ?? "",
          })}
        </Text>
        <ModalFooter>
          <Button variant="default" onClick={closeDelete} size="sm">
            {t("configuration.cancel")}
          </Button>
          <Button color="red" onClick={confirmDeleteProf} size="sm">
            {t("configuration.delete")}
          </Button>
        </ModalFooter>
      </Modal>
    </>
  );
}

export function ConfigurationPage() {
  const { t } = useTranslation();

  return (
    <Stack gap="lg">
      <PageHeader title={t("configuration.title")} noMargin />

      <Tabs defaultValue="professions">
        <Tabs.List>
          <Tabs.Tab
            value="professions"
            leftSection={<IconBriefcase size={16} />}
          >
            {t("configuration.professions")}
          </Tabs.Tab>
          <Tabs.Tab value="locations" leftSection={<IconMap size={16} />}>
            {t("location.title")}
          </Tabs.Tab>
          <Tabs.Tab
            value="certifications"
            leftSection={<IconCertificate size={16} />}
          >
            {t("certification.title")}
          </Tabs.Tab>
          <Tabs.Tab value="numberFormats" leftSection={<IconHash size={16} />}>
            {t("numberFormat.title", "Number Formats")}
          </Tabs.Tab>
        </Tabs.List>

        <Tabs.Panel value="professions" pt="md">
          <ProfessionTab />
        </Tabs.Panel>

        <Tabs.Panel value="locations" pt="md">
          <LocationPage />
        </Tabs.Panel>

        <Tabs.Panel value="certifications" pt="md">
          <CertificationPage />
        </Tabs.Panel>

        <Tabs.Panel value="numberFormats" pt="md">
          <NumberFormatTab />
        </Tabs.Panel>
      </Tabs>
    </Stack>
  );
}